1. Field of the Invention
The present invention relates to a flexible seamed endless belt. More particularly, the present invention relates to a flexible seamed endless belt that has a seamed portion as thick as the other portion and has high strength and good smoothness.
2. Description of the Related Art
Endless belts are widely used for transmission of rotary motion from power sources such as electric motors. They are usually formed from a flat elongated rectangular or parallelogramatic material by joining its opposing ends. Joining may be accomplished by bonding, sewing, or stapling. The resulting joints often present steps and mechanical discontinuity which impair accurate transmission of rotary motion. Consequently, they cannot be used as photoreceptors, intermediate sheets, image transport devices, fusing members, transfix devices, and the like in electrostatographic and electrographic image forming and processing machines. These machines need an endless belt free of joint or an endless belt with a specially designed joint which has no adverse effect on accurate transmission of rotary motion.
Unfortunately, joint-free endless belts need a complex technology which leads to high production cost and hampers mass production. This is true with large endless belts.
Improvements have been made in joined endless belts such that joints substantially do not affect accurate transmission of rotary motion. One way to achieve this object was to make butt joints by heat fusion bonding, ultrasonic fusion bonding, or adhesive bonding.
The disadvantage of endless belts produced in this manner is that the joint is not sufficiently strong and hence liable to break due to repeated flexural and frictional stresses. This leads to their short lives.
There is disclosed in Japanese Patent Laid-open No. 8-99737 (1996) a new endless belt which has been contrived to tackle the above-mentioned problem. This endless belt is formed from a flat material whose opposing ends have engageable structures to join them together. The resulting joint is greatly improved in strength. Unfortunately, this technology, which employs a solid thermoplastic adhesive to make the joint, cannot be applied to endless belts made of thermally vulnerable materials.